[FEATURE]: support adaptive thinking for claude sonnet 4.6

[tctev]

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

I noticed Opus 4.6 already uses adaptive thinking in ProviderTransform.variants, but Sonnet 4.6 still falls back to type: "enabled" with budgetTokens.

Anthropic now recommends adaptive thinking for both Opus 4.6 and Sonnet 4.6, so it would be great to align Sonnet 4.6 with the same behavior.

Requested update:

• include Sonnet 4.6 in adaptive model detection
• return adaptive variants (low, medium, high, max) for Anthropic, Gateway, and Bedrock paths
• keep current manual budgetTokens behavior for other Anthropic models

I opened PR #14283 with this change plus tests.

[github-actions]

This issue doesn't fully meet our contributing guidelines.

What needs to be fixed:

• This appears to be a feature request, but it does not use the required Feature Request template. Feature request titles must start with [FEATURE]: and include the required verification checkbox confirming you've searched for existing issues.

Please edit this issue to address the above within 2 hours, or it will be automatically closed.

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This issue might be a duplicate of existing issues. Please check:

• Support adaptive thinking for Claude Opus 4.6 #12485: Support adaptive thinking for Claude Opus 4.6 — covers the same ProviderTransform.variants adaptive thinking change; [FEATURE]: support adaptive thinking for claude sonnet 4.6 #14284 extends it to Sonnet 4.6 specifically.

If you believe this was flagged incorrectly, please let a maintainer know.

[github-actions]

Thanks for updating the issue! It now follows the contributing guidelines and the feature request template. We appreciate the clear description of the current vs. requested behavior.

[R44VC0RP]

Does the functionality when running ctrl + t achieve what you are trying to do?